| Author |
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Jack Zwick
Guest
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 Posted:
Fri Nov 26, 2004 10:10 am Post subject:
Re: Wireless "G" networking-When? |
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In article <10qdhlagak57oc3@news.supernews.com>,
Scott Peterson <scottp4.removethistoreply@mindspring.com> wrote:
| Quote: | The problem that if you run mixed b & g your entire wireless network
may be held back to speed of the b devices.
Scott Peterson
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You must have it confused with USB.
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Randy S.
Guest
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| Posted:
Fri Nov 26, 2004 6:16 pm Post subject:
Re: Wireless "G" networking-When? |
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| Quote: | The problem that if you run mixed b & g your entire wireless network
may be held back to speed of the b devices.
Scott Peterson
You must have it confused with USB.
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No, Scot's right, it has been shown that the throughput of 802.11g
devices is decreased dramatically (nearly to "b" levels) in a mixed mode
(versus an all "g") network.
Source: http://www.wi-fiplanet.com/tutorials/article.php/990101
Relevent Exceprt:
"3.4.3 Superior Performance
The current draft 802.11g specification provides for raw data rates of
54 Mbps and a 100-m range-numbers that are comparable to the 802.11a
standard. In terms of actual data throughput, single-mode 802.11g
networks will handle approximately 27 to 30 Mbps, which is comparable to
the performance of single-mode 802.11a and dual-band 802.11a+b networks.
However, for dual-mode 802.11g networks in which 802.11g and 802.11b
equipment coexist, the throughput of the 802.11g components drops to 20
Mbps or less due to the channel time sharing required to support
dual-mode operation.
In order to coexist with legacy 802.11b systems, 802.11g clients must
delay their transmissions to accommodate 802.11b clients, which cannot
"see" them. At a given data rate, the effective throughput is
proportional to the on-air time. The channel time-sharing operation of
dual-mode 802.11g reduces effective throughput, and as the number of
802.11b clients increases, the air time available for 802.11g clients
decreases, which leads to a larger drop in throughput. It is believed
that in the presence of 802.11b clients, the throughput of dual-mode
802.11g networks will not exceed that of a single 802.11b network."
Randy S. |
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Chris Nowak
Guest
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| Posted:
Sat Nov 27, 2004 12:12 am Post subject:
Re: Wireless "G" networking-When? |
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| Quote: | No, Scot's right, it has been shown that the throughput of 802.11g
devices is decreased dramatically (nearly to "b" levels) in a mixed mode
(versus an all "g") network.
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Eh, not entirely...
Relevent Excerpt from Relevant Excerpt:
| Quote: | Source: http://www.wi-fiplanet.com/tutorials/article.php/990101
At a given data rate, the effective throughput is
proportional to the on-air time. The channel time-sharing operation of
dual-mode 802.11g reduces effective throughput, and as the number of
802.11b clients increases, the air time available for 802.11g clients
decreases, which leads to a larger drop in throughput.
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You will only see the significant decrease with it is interacting with
the network. If your TiVo is the only 11b device on the network, and
you aren't constantly transferring video, it shouldn't hurt you all that
much.
There is always interaction between the 11b devices and the network
(beacon signals, etc), but it is discrete and very short, so a large
percentage of the time (unless you are actually sending traffic) you
will see 11g speeds for the 11g devices.
While transferring video (long time), or while getting service data
(shorter time), your throughput will severely degrade.
This, to me, is a fair tradeoff depending on the equipment you have
available.
Of course, you might want to look into an 802.11g bridge device like
they use for XBoxes and such (Or Airport Express if you have that sort
of infrastructure, etc)... and plug that into a wired USB adapter...
an extra chunk of change, but clean signal-wise.
Chris |
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Randy S.
Guest
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| Posted:
Sat Nov 27, 2004 6:11 am Post subject:
Re: Wireless "G" networking-When? |
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| Quote: | You will only see the significant decrease with it is interacting with
the network. If your TiVo is the only 11b device on the network, and
you aren't constantly transferring video, it shouldn't hurt you all that
much.
There is always interaction between the 11b devices and the network
(beacon signals, etc), but it is discrete and very short, so a large
percentage of the time (unless you are actually sending traffic) you
will see 11g speeds for the 11g devices.
While transferring video (long time), or while getting service data
(shorter time), your throughput will severely degrade.
This, to me, is a fair tradeoff depending on the equipment you have
available.
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I would agree with you here, however I just wanted to point out that
Scot was correct, as another poster had said he must've been talking
about USB speeds or something.
I wouldn't let a mixed mode environment prevent me from buying "G"
devices, the cost differential is minimal, even if you don't manage to
get full performance out of them until you upgrade all your devices.
Likely the impact is minimal, though. As I work in a more Enterprise
(University) environment, I tend to think about devices in constant use,
so in most situations that I would encounter the speed degradation would
be more significant (though 802.11b compatibility still easily trumps that).
Randy S. |
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